Plasma etch method for forming plasma etched silicon layer

ABSTRACT

A method for forming an etched silicon layer. There is first provided a first substrate having formed thereover a first silicon layer. There is then etched the first silicon layer to form an etched first silicon layer while employing a plasma etch method employing a plasma reactor chamber in conjunction with a plasma etchant gas composition which upon plasma activation provides at least one of an active bromine containing etchant species and an active chlorine containing etchant species. Within the plasma etch method: (1) a cleaned plasma reactor chamber is seasoned to provide a seasoned plasma reactor chamber having a seasoning polymer layer formed therein; (2) the first silicon layer is etched to form the etched first silicon layer within the seasoned plasma reactor chamber; and (3) the seasoning polymer layer is cleaned from the seasoned plasma reactor chamber to provide the cleaned plasma reactor chamber after etching the first silicon layer to form the etched first silicon layer within the seasoned plasma reactor chamber, prior to etching a second silicon layer to form an etched second silicon layer formed over a second substrate within the plasma reactor chamber while employing the plasma etch method in accord with (1), (2) and (3).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to methods for forming etchedsilicon layers within microelectronic fabrications. More particularly,the present invention relates to plasma etch methods for forming withattenuated plasma etch residue plasma etched silicon layers withinmicroelectronic fabrications.

2. Description of the Related Art

Microelectronic fabrications are formed from microelectronic substratesover which are formed patterned microelectronic conductor layers whichare separated by microelectronic dielectric layers.

As microelectronic fabrication integration levels have increased andmicroelectronic device and patterned microelectronic conductor layerdimensions have decreased, it has become more common in the art ofmicroelectronic fabrication to employ plasma etch methods for formingetched silicon layers, including but not limited to etchedmonocrystalline silicon layers, etched polycrystalline silicon layersand etched amorphous silicon layers, within microelectronicfabrications.

Such plasma etch methods often employ plasma etchant gas compositionswhich upon plasma activation provide active bromine and/or chlorinecontaining etchant species, such as may be derived, for example andwithout limitation, from etchant gases including but not limited tobromine, hydrogen bromide, chlorine and/or hydrogen chloride. Similarly,such etched silicon layers formed within microelectronic fabricationsmay include, but are not limited to: (1) partially etchedmonocrystalline silicon semiconductor substrate layers having shallowand/or deep isolation and/or capacitive trenches etched therein asemployed within semiconductor integrated circuit microelectronicfabrications, as well as; (2) fully etched and patterned polycrystallinesilicon non-substrate layers which may be employed as: (a) patternedpolysilicon conductor layers within microelectronic fabricationsincluding but not limited to semiconductor integrated circuitmicroelectronic fabrications, as well as; (b) gate electrodes withinfield effect transistors (FETs) employed within semiconductor integratedcircuit microelectronic fabrications.

Similarly, such etched silicon layers when formed within microelectronicfabrications while employing plasma etch methods which employ etchantgas compositions which upon plasma activation provide active bromineand/or chlorine containing etchant species are often formed in thepresence of silicon containing dielectric layers, such as but notlimited to silicon oxide dielectric layers, silicon nitride dielectriclayers and silicon oxynitride dielectric layers. The silicon containingdielectric layers may be formed as plasma etch mask hard mask patternedsilicon containing dielectric layers, or in the alternative as substratelayers, such as, for example and without limitation, as gate dielectricsilicon containing dielectric layers formed beneath gate electrodesformed within field effect transistors (FETs) employed withinsemiconductor integrated circuit microelectronic fabrications.

While plasma etch methods for forming etched silicon layers for usewithin microelectronic fabrications are thus desirable and common withinthe art of microelectronic fabrication, plasma etch methods for formingetched silicon layers for use within microelectronic fabrications arenonetheless not entirely without problems in the art of microelectronicfabrication. In that regard, it is known in the art of microelectronicfabrication that: (1) it is often difficult to reproducibly andcontrollably form while employing plasma etch methods etched siliconlayers with attenuated residue formation (such as but not limited toattenuated particulate contamination residue formation) withinmicroelectronic fabrications; and (2) in situations where the etchedsilicon layers are formed in the presence of silicon containingdielectric layers, it is often difficult to reproducibly andcontrollably form the etched silicon layers with enhanced selectivity ofthe plasma etch methods for the etched silicon layers with respect tothe silicon containing dielectric layers.

It is thus towards the goal of providing for use when fabricatingmicroelectronic fabrications plasma etch methods for reproducibly andcontrollably forming within microelectronic fabrications etched siliconlayers with: (1) attenuated residue formation (such as but not limitedto particulate contamination residue formation); and (2) enhancedselectivity of the plasma etch methods for the etched silicon layerswith respect to silicon containing dielectric layers when those etchedsilicon layers are formed in the presence of silicon containingdielectric layers, that the present invention is directed.

Various plasma processing methods have been disclosed in the art ofmicroelectronic fabrication for forming plasma processed microelectroniclayers with desirable properties within microelectronic fabrications.

For example, Gupta et al., in U.S. Pat. No. 5,456,796, discloses aplasma processing method for attenuating particulate generation anddeposition upon a substrate employed within a microelectronicfabrication when processing the substrate employed within themicroelectronic fabrication while employing the plasma processingmethod. The plasma processing method employs: (1) a rapid increase of aplasma power within a plasma reactor chamber to a high plasma powerlevel prior to introduction of the substrate into a plasma reactorchamber to thus provide for effective cleaning of the plasma reactorchamber prior to introduction of the substrate into the plasma reactorchamber, in conjunction with; (2) a slower increase of the plasma powerwithin the plasma reactor chamber subsequent to introduction of thesubstrate into the plasma reactor chamber in order to avoid circulationof particles within the plasma reactor chamber which would otherwisesettle upon the substrate.

In addition, Saito et al., in U.S. Pat. No. 5,681,424, disclose a plasmaprocessing method for cleaning a plasma reactor chamber within which isplasma etched a silicon layer formed over a substrate while employing ahydrogen bromide containing etchant gas composition, whilesimultaneously dissipating an electrostatic charge formed upon thesubstrate incident to use within a plasma apparatus employed within theplasma processing method of an electrostatic chuck for securing thesubstrate within the plasma reactor chamber. The plasma processingmethod employs an oxygen containing etchant gas composition forsimultaneously cleaning the reactor chamber and dissipating theelectrostatic charge formed upon the substrate.

Further, Leung et al., in U.S. Pat. No. 5,705,080, disclose a plasmaprocessing method for cleaning deposits from within a reactor chamber,including but not limited to a plasma reactor chamber, without damagingwithin the reactor chamber reactor components which are otherwisesensitive to the plasma processing method. The plasma processing methodemploys covering within the reactor chamber components which areotherwise sensitive to the plasma processing method prior to cleaningthe deposits from within the reactor chamber while employing the plasmaprocessing method.

Still further, Murugesh et al., in U.S. Pat. No. 5,811,356, disclose aplasma processing method and a plasma processing apparatus which providefor a reduced concentration of mobile ions and metal contaminants withina reactor chamber so that there may be fabricated within the reactorchamber microelectronic layers, particularly microelectronic dielectriclayers, with enhanced reliability. The method employs, when seasoningthe reactor chamber while employing the plasma processing method and theplasma processing apparatus, a bias radio frequency power density ofgreater than 0.051 watts per square millimeter and a seasoning time ofgreater than about 30 seconds.

Finally, Gupta, in U.S. Pat. No. 5,824,375, discloses a plasmaprocessing method and a plasma processing apparatus for reducingfluorine and other sorbable contaminants in a plasma reactor chamberemployed within a chemical vapor deposition (CVD) method, such as butnot limited to a plasma enhanced chemical vapor deposition (PECVD)method. The plasma processing method and the plasma processing apparatusemploy an inert plasma treatment of the plasma reactor chamber aftercleaning the plasma reactor chamber while employing a fluorinecontaining plasma etch method and prior to forming within the plasmareactor chamber while employing a plasma deposition method a passivatingseasoning layer within the plasma reactor chamber.

Desirable in the art of microelectronic fabrication are additionalplasma etch methods and materials which may be employed for reproduciblyand controllably forming with attenuated residue etched silicon layerswithin microelectronic fabrications with enhanced selectivity of theplasma etch methods for the etched silicon layers with respect tosilicon containing dielectric layers when the etched silicon layers areformed in the presence of silicon containing dielectric layers.

It is towards the foregoing objects that the present invention isdirected.

SUMMARY OF TEE INVENTION

A first object of the present invention is to provide a plasma etchmethod for reproducibly and controllably forming an etched silicon layerwithin a microelectronic fabrication.

A second object of the present invention is to provide a plasma etchmethod in accord with the first object of the present invention, wherethe etched silicon layer is reproducibly and controllably formed withattenuated residue (such as but not limited to particulate contaminationresidue).

A third object of the present invention is to provide a plasma etchmethod in accord with the first object of the present invention and thesecond object of the present invention, where the plasma etch methodreproducibly and controllably exhibits enhanced selectivity for theetched silicon layer with respect to a silicon containing dielectriclayer when the etched silicon layer is formed in the presence of thesilicon containing dielectric layer within the microelectronicfabrication.

A fourth object of the present invention is to provide a method inaccord with the first object of the present invention, the second objectof the present invention and the third object of the present invention,which method is readily commercially implemented.

In accord with the objects of the present invention, there is provided aplasma etch method for forming an etched silicon layer. To practice themethod of the present invention, there is first provided a firstsubstrate having formed thereover a first silicon layer. There is thenetched the first silicon layer to form an etched first silicon layerwhile employing a plasma etch method employing a plasma reactor chamberin conjunction with a plasma etchant gas composition which upon plasmaactivation provides at least one of an active bromine containing etchantspecies and an active chlorine containing etchant species, whereinwithin the plasma etch method: (1) a cleaned plasma reactor chamber isseasoned to provide a seasoned plasma reactor chamber having a seasoningpolymer layer formed therein; (2) the first silicon layer is etched toform the etched first silicon layer within the seasoned plasma reactorchamber; and (3) the seasoning polymer layer is cleaned from theseasoned plasma reactor chamber to provide the cleaned plasma reactorchamber after etching the first silicon layer to form the etched firstsilicon layer within the seasoned plasma reactor chamber, prior toetching a second silicon layer to form an etched second silicon layerformed over a second substrate within cleaned plasma reactor chamberwhile employing the plasma etch method in accord with (1), (2) and (3).

The present invention provides a plasma etch method for reproducibly andcontrollably forming an etched silicon layer within a microelectronicfabrication, where the etched silicon layer is formed with attenuatedresidue (such as but not limited to particulate residue) and where theplasma etch method exhibits enhanced selectivity for the etched siliconlayer with respect to a silicon containing dielectric layer when theetched silicon layer is formed in the presence of the silicon containingdielectric layer within the microelectronic fabrication. The presentinvention realizes the foregoing objects by employing within the presentinvention: (1) a cleaned plasma reactor chamber seasoning to provide aseasoned plasma reactor chamber having a seasoning polymer layer formedtherein; (2) a single substrate silicon layer etching within theseasoned plasma reactor chamber; and (3) a cleaning of the seasoningpolymer layer from the seasoned plasma reactor chamber to provide thecleaned plasma reactor chamber, prior to etching a second silicon layerto form an etched second silicon layer formed over a second substratewhile employing the preceding steps (1), (2) and (3).

The method of the present invention is readily commercially implemented.The present invention employs an apparatus which is generallyconventional in the art of microelectronic fabrication. Since it is aprocess control and materials selection which provides at least in partthe present invention, rather than the existence of methods andapparatus which provides the present invention, the method of thepresent invention is readily commercially implemented.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features and advantages of the present invention areunderstood within the context of the Description of the PreferredEmbodiment, as set forth below. The Description of the PreferredEmbodiment is understood within the context of the accompanyingdrawings, which form a material part of this disclosure, wherein:

FIG. 1, FIG. 2, FIG. 3 and FIG. 4 show a series of schematiccross-sectional diagrams of a plasma reactor chamber at progressivestages within a plasma etch method in accord with the present invention.

FIG. 5 shows a plot of Plasma Reactor Chamber Seasoning Polymer Contentversus Number of Substrates Processed, for a series of substratesprocessed within a plasma reactor chamber in accord with the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention provides a plasma etch method for reproducibly andcontrollably forming an etched silicon layer within a microelectronicfabrication, where the etched silicon layer is formed with attenuatedresidue (such as but not limited to particulate contamination residue)and where the plasma etch method exhibits enhanced selectivity for theetched silicon layer with respect to a silicon containing dielectriclayer when the etched silicon layer is formed in the presence of thesilicon containing dielectric layer within the microelectronicfabrication. The method of the present invention realizes the foregoingobjects by employing within the plasma etch method: (1) a seasoning of acleaned plasma reactor chamber to form a seasoned plasma reactor chamberhaving a seasoning polymer layer formed therein; (2) a single substratesilicon layer etching within the seasoned plasma reactor chamber; and(3) a cleaning of the seasoning polymer layer from the seasoned plasmareactor chamber to provide the cleaned plasma reactor chamber, prior toetching a second silicon layer to form an etched second silicon layerformed over a second substrate while employing the preceding steps (1),(2) and (3).

The plasma etch method of the present invention may be employed forforming from silicon layers including but not limited to monocrystallinesilicon layers, polycrystalline silicon layers and amorphous siliconlayers etched silicon layers including but not limited to etchedmonocrystalline silicon layers, etched polycrystalline silicon layersand etched amorphous silicon layers within microelectronic fabricationsincluding but not limited to integrated circuit microelectronicfabrications, ceramic substrate microelectronic fabrications, solar celloptoelectronic microelectronic fabrications, sensor image arrayoptoelectronic microelectronic fabrications and display image arrayoptoelectronic microelectronic fabrications.

Referring now to FIG. 1 to FIG. 4, there is shown a series schematiccross-sectional diagrams illustrating a plasma reactor chamber atprogressive stages within a plasma etch method in accord with thepresent invention. Shown in FIG. 1 is a schematic cross-sectionaldiagram of the plasma reactor chamber at an early stage in practice ofthe plasma etch method of the present invention.

Shown in FIG. 1 is a cleaned plasma reactor chamber 10 having fabricatedtherein a platen 12. As is understood by a person skilled in the art,plasma reactor chambers are available in any of several types, sizes andconfigurations as are needed and desirable to plasma process any ofseveral types of substrates as are employed within various types ofmicroelectronic fabrications. Various of such types, sizes andconfigurations of plasma reactor chambers are disclosed within thevarious references cited within the Description of the Related Art, thedisclosures of which references are incorporated herein fully byreference. As is similarly understood by a person skilled in the art,the platen 12 as illustrated within the schematic cross-sectionaldiagram of FIG. 1 is sized appropriately to accommodate a substrateemployed within a microelectronic fabrication which is fabricatedemploying the plasma etch method of the present invention.

Referring now to FIG. 2, there is shown a schematic cross-sectionaldiagram illustrating a plasma reactor chamber at a further stage withinthe plasma etch method in accord with the present invention.

Shown in FIG. 2 is a plasma reactor chamber otherwise equivalent to thecleaned plasma reactor chamber 10 whose schematic cross-sectionaldiagram is illustrated in FIG. 1, but wherein there is formed uponinterior surfaces of the cleaned plasma reactor chamber 10 a seasoningpolymer layer 14, thus forming from the cleaned plasma reactor chamber10 a seasoned plasma reactor chamber 10′. Within the preferredembodiment of the present invention, the seasoning polymer layer 14 istypically and preferably formed of a seasoning polymer material selectedfrom the group including but not limited to: (1) a silicon and brominecontaining seasoning polymer material; (2) a silicon, bromine and oxygencontaining seasoning polymer material; (3) a silicon and chlorineseasoning polymer material, (4) a silicon, chlorine and oxygencontaining seasoning polymer material; (5) a silicon, bromine andchlorine seasoning polymer material; and (6) a silicon, bromine,chlorine and oxygen seasoning polymer material.

Within the preferred embodiment of the present invention, the seasoningpolymer layer 14 may be formed employing any one of at least threeseasoning polymer layer formation methods.

The first of the at least three seasoning polymer layer formationmethods is a dummy wafer seasoning polymer layer formation method whichemploys in the alternative: (1) a silicon oxide coated dummy wafer inconjunction with a seasoning plasma etch method employing at least oneof a bromine containing etchant gas and a chlorine containing etchantgas; (2) a silicon oxide coated dummy wafer in conjunction with aseasoning plasma etch method employing at least one of a brominecontaining etchant gas and a chlorine containing etchant gas, inaddition to an oxygen containing etchant gas; and (3) a silicon dummywafer in conjunction with a seasoning plasma etch method employing atleast one of a bromine containing etchant gas and a chlorine containingetchant gas, in addition to an oxygen containing etchant gas. Within thepreferred embodiment of the present invention, the bromine containingetchant gas is typically and preferably selected from the groupconsisting of hydrogen bromide and bromine, while the chlorinecontaining etchant gas is typically and preferably selected from thegroup consisting of hydrogen chloride and chlorine. Similarly, withinthe preferred embodiment of the present invention, the oxygen containingetchant gas is typically and preferably selected from the groupconsisting of oxygen, ozone, nitrous oxide and nitric oxide. Mosttypically and preferably, the bromine containing etchant gas is hydrogenbromide, the chlorine containing etchant gas is chlorine or hydrogenchloride and the oxygen containing etchant gas is oxygen.

Typically and preferably, the dummy wafer seasoning method will employwhen forming the seasoning polymer layer 14 within a seasoned plasmareactor chamber 10′ employed for plasma processing an eight inchdiameter substrate: (1) a plasma reactor chamber 10 pressure of fromabout 1 to about 500 mtorr; (2) a source radio frequency power of fromabout 10 to about 2000 watts at a source radio frequency of from 2 MHzto 13.56 MHZ, and an external bias power of up to about 500 watts; (3) aplasma reactor chamber 10 temperature and a dummy wafer temperature offrom about 20 to about 200 degrees centigrade; (4) a bromine and/orchlorine containing etchant gas flow rate of from about 10 to about 200standard cubic centimeters per minute (sccm); (5) an oxygen containingetchant gas flow rate of from about 1 to about 50 standard cubiccentimeters per minute (sccm); (6) a backside cooling gas, typically andpreferably but not exclusively helium, at a pressure of from about 1 toabout 50 torr and a flowrate of from about 2 to about 50 standard cubiccentimeters per minute (sccm); (7) a magnetic field of up to about 200gauss; and (8) a plasma seasoning time of from about 5 to about 120seconds.

The second of the at least three seasoning polymer layer formationmethods is an in-situ seasoning polymer layer formation method wherein aproduct substrate having formed exposed thereover a silicon layer, or asilicon layer in the presence of a silicon containing dielectric layer,such as but not limited to a silicon oxide dielectric layer, a siliconnitride dielectric layer or a silicon oxynitride dielectric layer, isplasma etched at a comparatively lower plasma power and a comparativelyhigher reactor chamber pressure to form the seasoning polymer layer 14within the seasoned reactor chamber 10′ while not damaging the productsubstrate. Under such circumstances when employing an in-situ seasoningmethod, there is employed: (1) a silicon containing seasoning polymerlayer forming gas; (2) at least one of a bromine containing seasoningpolymer layer forming gas and a chlorine containing seasoning polymerlayer forming gas; and (3) an optional oxygen containing seasoningpolymer layer forming gas, where the latter two seasoning polymer layerforming gases are provided in accord with choices for the bromine and/orchlorine containing etchant gas and the oxygen containing etchant gas asdisclosed above as employed within the dummy wafer seasoning polymerlayer formation method. The silicon containing seasoning polymer layerforming gas may be selected from the group including but not limited tosilicon bromide (which may also serve as a bromine containing seasoningpolymer layer forming gas), silicon tetrachloride (which may also serveas a chlorine containing seasoning polymer layer forming gas) andsilane.

Typically and preferably, the in-situ seasoning polymer layer formingmethod will employ when forming the seasoning polymer layer 14 within aseasoned plasma reactor chamber 10′ employed for plasma processing aneight inch diameter substrate: (1) a plasma reactor chamber pressure offrom about 50 to about 1000 mtorr; (2) a radio frequency source power offrom about 10 to about 1000 watts at a source radio frequency of from 2MHZ to 13.56 MHZ, without an external bias source; (3) a plasma reactorchamber 10 and product substrate temperature of from about 20 to about200 degrees centigrade; (4) a silicon containing seasoning polymer layerforming gas flow rate of from about 1 to about 200 standard cubiccentimeters per minute (sccm); (5) a bromine and/or chlorine containingseasoning polymer layer forming gas flow rate of from about 10 to about200 standard cubic centimeters per minute (sccm); (6) an optional oxygencontaining seasoning polymer layer forming gas flow rate of from about 1to about 50 standard cubic centimeters per minute (sccm); (7) a backsidecooling gas, typically and preferably but not exclusively helium, at apressure of from about 1 to about 50 torr and a flowrate of from about 2to about 50 standard cubic centimeters per minute (sccm); (8) a magneticfield of up to about 200 gauss; and (9) a plasma seasoning time of fromabout 5 to about 120 seconds.

Finally, within the preferred embodiment of the present invention thethird of the at least three seasoning polymer layer forming methods is awaferless seasoning polymer layer forming method which employs aseasoning polymer layer forming gas composition employing depositionparameters and limits as employed for the in-situ seasoning polymerlayer forming method, as above, but without the presence of the productsubstrate, or any other substrate, within the cleaned plasma reactorchamber 10.

Within the preferred embodiment of the present invention there mayadditionally be employed within any of the foregoing three seasoningpolymer layer forming methods an optional fluorine containing etchantgas/seasoning gas, such as but not limited to a nitrogen trifluoridefluorine containing etchant gas/seasoning gas or a sulfur hexafluoridefluorine containing etchant gas/seasoning gas, but not a fluorocarboncontaining etchant gas/seasoning gas, at a flow rate of from about 1 toabout 100 standard cubic centimeters per minute, more preferably fromabout 1 to about 20 standard cubic centimeters per minute (sccm).Similarly, and in particular with respect to the waferless seasoningpolymer layer forming method, it may also be desirable within thepresent invention to employ within the cleaned plasma reactor chamber 10a ceramic chuck, rather than a polyimide coated chuck, in order to avoidattack of a polyimide layer formed upon the polyimide coated chuck bythe plasma seasoning polymer layer forming methods.

Referring now to FIG. 3, there is shown a schematic cross-sectionaldiagram illustrating a plasma reactor chamber at a further stage in theplasma etch method in accord with the present invention.

Shown in FIG. 3 is a plasma reactor chamber otherwise equivalent to theseasoned plasma reactor chamber 10′ as illustrated within the schematiccross-sectional diagram of FIG. 2, but wherein there is positioned uponthe platen 12 a substrate 16 which is etched within a silicon layer etchplasma 18 which simultaneously supplements the seasoning polymer layer14 to form a supplemented seasoning polymer layer 14′ within asupplementally seasoned plasma reactor chamber 10″.

Although not specifically illustrated within the schematiccross-sectional diagram of FIG. 3, the substrate 16 has formed thereovera silicon layer which is etched to form an etched silicon layer withinthe silicon layer etch plasma 18. The silicon layer may be formed from asilicon material selected from the group consisting of monocrystallinesilicon materials, polycrystalline silicon materials and amorphoussilicon materials. Typically and preferably, although not exclusively,the silicon layer will be masked with a mask layer which may be formedfrom a silicon containing hard mask dielectric material, such as but notlimited to a silicon oxide hard mask dielectric material, a siliconnitride hard mask dielectric material or a silicon oxynitride hard maskdielectric material, or in the alternative a photoresist mask material,although photoresist mask materials are not preferred since they mayeither add carbon to the supplemented seasoning polymer layer 14′, or inthe alternative add various contaminants to the substrate 16. Similarly,the silicon layer will often be formed in the presence of a siliconcontaining dielectric layer, which if not employed for forming the hardmask layer may otherwise be in contact with the silicon layer, such as,for example and without limitation as formed immediately beneath thesilicon layer.

Within the preferred embodiment of the present invention with respect tothe silicon layer etch plasma 18, the silicon layer etch plasma 18typically and preferably employs an etchant gas composition which uponplasma activation forms at least one of an active bromine containingetchant species and an active chlorine containing etchant species (suchas may be formed from an etchant gas including but not limited tohydrogen bromide, bromine, hydrogen chloride and/or chlorine), alongwith an optional oxygen containing etchant species (such as but notlimited to oxygen, ozone, nitrous oxide or nitric oxide) and an optionalfluorine containing etchant species (such as but not limited to nitrogentrifluoride and sulfur hexafluoride). More preferably, the silicon layeretch plasma 18 employs an etchant gas composition comprising hydrogenbromide, oxygen and nitrogen trifluoride.

When etching a silicon layer to form an etched silicon layer over aneight inch diameter substrate 16 within the supplementally seasonedplasma reactor chamber 10″ as illustrated within the schematiccross-sectional diagram of FIG. 3, the silicon layer etch plasma 18 alsoemploys: (1) a reactor chamber pressure of from about 1 to about 500mtorr, (2) a radio frequency source power of from about 10 to about 2000watts at a source radio frequency of from 2 MHz to 13.56 MHz and anexternal bias power of up to about 500 watts; (3) a substrate 16 andsupplementally seasoned plasma reactor chamber 10″ temperature of fromabout 20 to about 200 degrees centigrade; (4) a hydrogen bromide flowrate of from about 10 to about 200 standard cubic centimeters per minute(sccm); (5) an oxygen flow rate of from about 1 to about 50 standardcubic centimeters per minute (sccm); (6) a nitrogen trifluoride flowrate of from about 1 to about 50 standard cubic centimeters per minute(sccm); (7) a backside cooling gas, typically and preferably but notexclusively helium, at a pressure of from about 1 to about 50 torr and aflowrate of from about 2 to about 50 standard cubic centimeters perminute (sccm); and (8) a magnetic field of up to about 200 gauss.

Referring now to FIG. 4, there is shown a schematic cross-sectionaldiagram illustrating a plasma reactor chamber at a further stage withinthe plasma etch method in accord with the present invention.

Shown in FIG. 4 is a schematic cross-sectional diagram of a plasmareactor chamber otherwise equivalent to the supplementally seasonedplasma reactor chamber 10″ whose schematic cross-sectional diagram isillustrated in FIG. 3, but wherein the plasma reactor chamber has beencleaned of the supplemented seasoning polymer layer 14′ and returned toa condition equivalent, although not necessarily identical, to thecondition of the cleaned plasma reactor chamber 10 as illustrated withinthe schematic cross-sectional diagram of FIG. 1.

To thus strip from within the supplementally seasoned plasma reactorchamber 10″ as illustrated within the schematic cross-sectional diagramof FIG. 3 the supplemented seasoning polymer layer 14′ to provide thecleaned plasma reactor chamber 10 whose schematic cross-sectionaldiagram is illustrated in FIG. 4 and FIG. 1, there is typically andpreferably employed a plasma stripping method, typically and preferablyemploying an etchant gas composition which upon plasma activationprovides an active fluorine containing etchant species. More typicallyand preferably, the etchant gas composition employs at least one ofnitrogen trifluoride and sulfur hexafluoride, and preferably not afluorocarbon etchant gas.

When stripping the supplemented seasoning polymer layer 14′ from withinthe supplementally seasoned plasma reactor chamber 10″ which is employedin processing an eight inch diameter substrate 16, the plasma strippingmethod also employs: (1) a supplementally seasoned plasma reactorchamber 10″ pressure of from about 50 to about 500 mtorr; (2) a sourceradio frequency of from about 100 to about 2000 watts at a source radiofrequency of 2 MHZ to 13.56 MHZ, and a bias power of up to about 500watts; (3) a supplementally seasoned plasma reactor chamber 10″temperature of from about 20 to about 200 degrees centigrade; (4) anitrogen trifluoride or a sulfur hexafluoride flow rate of from about 10to about 500 standard cubic centimeters per minute (sccm); (5) abackside cooling gas, typically and preferably but not exclusivelyhelium, at a pressure of from about 1 to about 50 torr and a flowrate offrom about 2 to about 50 standard cubic centimeters per minute (sccm);and (6) a magnetic field of up to about 200 gauss.

Although not specifically illustrated within the schematiccross-sectional diagram of FIG. 4, the plasma stripping method may alsooptionally employ a dummy wafer. Similarly, and in particular when adummy wafer is not employed within the plasma stripping method, it mayalso be desirable within the present invention to employ within thesupplementally seasoned plasma reactor chamber 10″ a ceramic chuck,rather than a polyimide coated chuck, in order to avoid attack of apolyimide layer formed upon the polyimide coated chuck by the plasmastripping method.

Upon stripping from the supplementally seasoned plasma reactor chamber10″ the supplemented seasoning polymer layer 14′ as illustrated withinthe schematic cross-sectional diagram of FIG. 3 to provide the cleanedreactor chamber 10 as illustrated within the schematic cross-sectionaldiagram of FIG. 4, there is provided a cleaned reactor chamber withinwhich may be processed a second substrate in accord with a process flowin accord with FIG. 1, FIG. 2 and FIG. 3, where the second substrate hasformed thereover a second silicon layer which is etched to form anetched second silicon layer.

By employing within the method of the present invention a plasma reactorchamber seasoning, a silicon layer etching and a plasma reactor chambercleaning for each single substrate fabricated within the plasma reactorchambers as illustrated within the schematic cross-sectional diagrams ofFIG. 1 to FIG. 4, there is reproducibly and controllably provided withan enhanced uniformity an etched silicon layer formed over the substrate16, where the etched silicon layer is reproducibly and controllablyformed with an attenuated residue (such as particulate contaminationresidue) formed upon .the etched silicon layer formed over the substrate16 and an attenuated etching of a silicon containing dielectric layerformed in the presence of the etched silicon layer.

Referring now to FIG. 5, there is shown a graph of Plasma ReactorChamber Seasoning Polymer Content versus Number of Substrates Processedfor a plasma reactor chamber in accord with the preferred embodiment ofthe present invention. As is illustrated by the legend which accompaniesFIG. 5, there is shown within FIG. 5 by means of the dashed upwardlypointing arrows a portion of the process of the present invention whichis directed towards forming the seasoning polymer layer within theseasoned plasma reactor chamber. Similarly, in conjunction with theseasoning polymer layer there is shown by addition of the solid upwardlypointing arrows the supplemented seasoning polymer layer content withinthe supplementally seasoned reactor chamber. Finally, there is shown bythe downwardly pointed arrows the results of cleaning the reactorchamber of the present invention to remove therefrom the supplementedseasoning polymer layer.

As is similarly also illustrated within the graph of FIG. 5 there is ashaded target range for seasoning polymer content within which it isdesired to operate the plasma reactor chamber while employing the methodof the present invention. Above the shaded range of seasoning polymercontent the thickness of seasoning polymer layer becomes sufficientlythick such that it is believed that flaking occurs and contributes toparticulate contamination upon a substrate over which is formed asilicon layer which is etched within the plasma reactor chamber.Similarly, under conditions where the seasoning polymer layer is formedwithin the plasma reactor chamber of a content less than a minimalrequisite content, there is observed a loss in selectivity for etchingof the silicon layer formed over the substrate with respect to a siliconcontaining dielectric layer also formed over the substrate.

As is understood by a person skilled in the art, although: (1) thecleaned reactor chamber 10 as illustrated within the schematiccross-sectional diagram of FIG. 1 is disclosed as equivalent, althoughnot necessarily identical, to the cleaned reactor chamber 10 asillustrated within the schematic cross-sectional diagram of FIG. 4; and(2) it is typical and preferred within the present invention that thecleaned plasma reactor chamber 10 as illustrated within the schematiccross-sectional diagram of FIG. 1 be formed employing the plasmastripping method as employed for forming the cleaned reactor chamber 10as illustrated within the schematic cross-sectional diagram of FIG. 4from the supplementally seasoned plasma reactor chamber 10″ asillustrated within the schematic cross-sectional diagram of FIG. 3, wheninitiating the method of the present invention, the cleaned reactorchamber 10 as illustrated within the schematic cross-sectional diagramof FIG. 1 may initially be formed employing alternative methods toassure its cleanliness, including but not limited to other plasmastripping methods and plasma conditioning methods.

Similarly, as is understood by a person skilled in the art, although thepresent invention is disclosed within the context of a multi-cycleseasoning/etching/cleaning method for reproducibly and controllablyforming a series of etched silicon layers with desirable properties overa series of substrates employed within a microelectronic fabrication,the method of the present invention may alternatively equivalently bedisclosed and claimed as a multi-cycle cleaning/seasoning/etchingmethod, or alternatively to a lesser extent as a multi-cycleetching/cleaning/seasoning method, for forming an identical series ofetched silicon layers with the desirable properties over an identicalseries of substrates, since the present invention provides a multi-cyclemethod where the particular starting point for describing the method maybe arbitrarily chosen.

Finally, as is understood by a person skilled in the art, the preferredembodiment of the present invention is illustrative of the presentinvention rather than limiting of the present invention. Revisions andmodifications may be made to methods, materials, structures anddimensions through which is provided an etched silicon layer within amicroelectronic fabrication in accord with the preferred embodiment ofthe present invention, while still providing an etched silicon layerwithin a microelectronic fabrication in accord with the presentinvention, in accord with the accompanying claims.

What is claimed is:
 1. A method for forming an etched silicon layercomprising: providing a first substrate having formed thereover a firstsilicon layer; etching the first silicon layer to form an etched firstsilicon layer while employing a plasma etch method employing a plasmareactor chamber in conjunction with a plasma etchant gas compositionwhich upon plasma activation provides at least one of an active brominecontaining etchant species and an active chlorine containing etchantspecies, wherein within the plasma etch method: (1) a cleaned plasmareactor chamber is seasoned to provide a seasoned plasma reactor chamberhaving a seasoning polymer layer formed therein; wherein the seasoningmethod is a waferless seasoning method employing: (a) a siliconcontaining seasoning polymer layer forming gas; and (b) a bromine and/orchlorine containing etchant gas; (2) the first silicon layer is etchedto form the etched first silicon layer within the seasoned plasmareactor chamber; wherein the first silicon layer etch step, when usingan eight inch diameter substrate, employs: a reactor chamber pressure offrom about 1 to 500 mTorr; a radio frequency source power of from about10 to 2000 watts at a source radio frequency of from about 2 to 13.56MHz and an external bias power of up to about 500 watts; a substratetemperature and a seasoned plasma reactor chamber temperature of fromabout 20 to 200° C.; a bromine and/or chlorine containing etchant gasflow rate of from about 10 to 200 sccm; an oxygen flow rate of fromabout 1 to 50 sccm; a nitrogen trifluoride flow rate of from about 1 to50 sccm; a backside cooling gas pressure of from about 1 to 50 torr anda flow rate of from about 2 to 50 sccm; and a magnetic field of up toabout 200 gauss; and (3) the seasoning polymer layer is cleaned from theseasoned plasma reactor chamber to provide the cleaned plasma reactorchamber after etching the first silicon layer to form the etched firstsilicon layer within the seasoned plasma reactor chamber prior toetching a second substrate having formed thereover a second siliconlayer to form an etched second silicon layer formed over the secondsubstrate within the plasma reactor chamber while employing the plasmaetch method in accord with (1), (2) and (3).
 2. A method for forming anetched monocrystalline silicon layer comprising: providing a firstsubstrate having formed thereover a first monocrystalline silicon layer;etching the first monocrystalline silicon layer to form an etched firstmonocrystalline silicon layer while employing a plasma etch methodemploying a plasma reactor chamber in conjunction with a plasma etchantgas composition which upon plasma activation provides at least one of anactive bromine containing etchant species and an active chlorinecontaining etchant species, wherein within the plasma etch method: (1) acleaned plasma reactor chamber is seasoned to provide a seasoned plasmareactor chamber having a seasoning polymer layer formed therein; whereinthe seasoning method is a waferless seasoning method employing: (a) asilicon containing seasoning polymer layer forming gas; and (b) abromine and/or chlorine containing etchant gas; (2) the firstmonocrystalline silicon layer is etched to form the etched firstmonocrystalline silicon layer within the seasoned plasma reactorchamber; wherein the first monocrystalline silicon layer etch step, whenusing an eight inch diameter substrate, employs: a reactor chamberpressure of from about 1 to 500 mTorr; a radio frequency source power offrom about 10 to 2000 watts at a source radio frequency of from about 2to 13.56 MHz and an external bias power of up to about 500 watts; asubstrate temperature and a seasoned plasma reactor chamber temperatureof from about 20 to 200° C.; a bromine and/or chlorine containingetchant gas flow rate of from about 10 to 200 sccm; an oxygen flow rateof from about 1 to 50 sccm; a nitrogen trifluoride flow rate of fromabout 1 to 50 sccm; a backside cooling gas pressure of from about 1 to50 torr and a flow rate of from about 2 to 50 sccm; and a magnetic fieldof up to about 200 gauss; and (3) the seasoning polymer layer is cleanedfrom the seasoned plasma reactor chamber to provide the cleaned plasmareactor chamber after etching the first monocrystalline silicon layer toform the etched first monocrystalline silicon layer within the seasonedplasma reactor chamber prior to etching a second substrate having formedthereover a second monocrystalline silicon layer to form an etchedsecond monocrystalline silicon layer formed over the second substratewithin the plasma reactor chamber while employing the plasma etch methodin accord with (1), (2) and (3).
 3. A method for forming an etchedpolycrystalline silicon layer comprising: providing a first substratehaving formed thereover a first polycrystalline silicon layer; etchingthe first polycrystalline silicon layer to form an etched firstpolycrystalline silicon layer while employing a plasma etch methodemploying a plasma reactor chamber in conjunction with a plasma etchantgas composition which upon plasma activation provides an active brominecontaining etchant species, wherein within the plasma etch method: (1) acleaned plasma reactor chamber is seasoned to provide a seasoned plasmareactor chamber having a seasoning polymer layer formed therein; whereinthe seasoning method is a waferless seasoning method employing: (a) asilicon containing seasoning polymer layer forming gas; and (b) abromine and/or chlorine containing etchant gas; (2) the firstpolycrystalline silicon layer is etched to form the etched firstpolycrystalline silicon layer within the seasoned plasma reactorchamber; wherein the first polycrystalline silicon layer etch step, whenusing an eight inch diameter substrate, employs: a reactor chamberpressure of from about 1 to 500 mTorr; a radio frequency source power offrom about 10 to 2000 watts at a source radio frequency of from about 2to 13.56 MHz and an external bias power of up to about 500 watts; asubstrate temperature and a seasoned plasma reactor chamber temperatureof from about 20 to 200° C.; a hydrogen bromide flow rate of from about10 to 200 sccm; an oxygen flow rate of from about 1 to 50 sccm; anitrogen trifluoride flow rate of from about 1 to 50 sccm; a backsidecooling gas pressure of from about 1 to 50 torr and a flow rate of fromabout 2 to 50 sccm; and a magnetic field of up to about 200 gauss; and(3) the seasoning polymer layer is cleaned from the seasoned plasmareactor chamber to provide the cleaned plasma reactor chamber afteretching the first polycrystalline silicon layer to form the etched firstpolycrystalline silicon layer within the seasoned plasma reactor chamberprior to etching a second substrate having formed thereover a secondpolycrystalline silicon layer to form an etched second polycrystallinesilicon layer formed over the second substrate within the plasma reactorchamber while employing the plasma etch method in accord with (1), (2)and (3).
 4. A method for forming an etched silicon layer comprising:providing a first substrate having formed thereover a first siliconlayer; etching the first silicon layer to form an etched first siliconlayer while employing a plasma etch method employing a plasma reactorchamber in conjunction with a plasma etchant gas composition which uponplasma activation provides at least one of an active bromine containingetchant species and an active chlorine containing etchant species,wherein within the plasma etch method: (1) a cleaned plasma reactorchamber is seasoned to provide a seasoned plasma reactor chamber havinga seasoning polymer layer formed therein; wherein the seasoning methodis a waferless seasoning method employing (a) a silicon containingseasoning polymer layer forming gas; and (b) a bromine and/or chlorinecontaining etchant gas; (2) the first silicon layer is etched to formthe etched first silicon layer within the seasoned plasma reactorchamber; and (3) the seasoning polymer layer is cleaned from theseasoned plasma reactor chamber to provide the cleaned plasma reactorchamber after etching the first silicon layer to form the etched firstsilicon layer within the seasoned plasma reactor chamber prior toetching a second substrate having formed thereover a second siliconlayer to form an etched second silicon layer formed over the secondsubstrate within the plasma reactor chamber while employing the plasmaetch method in accord with (1), (2) and (3).
 5. A method for forming anetched monocrystalline silicon layer comprising: providing a firstsubstrate having formed thereover a first monocrystalline silicon layer;etching the first monocrystalline silicon layer to form an etched firstmonocrystalline silicon layer while employing a plasma etch methodemploying a plasma reactor chamber in conjunction with a plasma etchantgas composition which upon plasma activation provides at least one of anactive bromine containing etchant species and an active chlorinecontaining etchant species, wherein within the plasma etch method: (1) acleaned plasma reactor chamber is seasoned to provide a seasoned plasmareactor chamber having a seasoning polymer layer formed therein; whereinthe seasoning method is a waferless seasoning method employing: (a) asilicon containing seasoning polymer layer forming gas; and (b) abromine and/or chlorine containing etchant gas; (2) the firstmonocrystalline silicon layer is etched to form the etched firstmonocrystalline silicon layer within the seasoned plasma reactorchamber; and a magnetic field of up to about 200 gauss; and (3) theseasoning polymer layer is cleaned from the seasoned plasma reactorchamber to provide the cleaned plasma reactor chamber after etching thefirst monocrystalline silicon layer to form the etched firstmonocrystalline silicon layer within the seasoned plasma reactor chamberprior to etching a second substrate having formed thereover a secondmonocrystalline silicon layer to form an etched second monocrystallinesilicon layer formed over the second substrate within the plasma reactorchamber while employing the plasma etch method in accord with (1), (2)and (3).
 6. A method for forming an etched polycrystalline silicon layercomprising: providing a first substrate having formed thereover a firstpolycrystalline silicon layer; etching the first polycrystalline siliconlayer to form an etched first polycrystalline silicon layer whileemploying a plasma etch method employing a plasma reactor chamber inconjunction with a plasma etchant gas composition which upon plasmaactivation provides an active bromine containing etchant species,wherein within the plasma etch method: (1) a cleaned plasma reactorchamber is seasoned to provide a seasoned plasma reactor chamber havinga seasoning polymer layer formed therein; wherein the seasoning methodis a waferless seasoning method employing: (a) a silicon containingseasoning polymer layer forming gas; and (b) a bromine and/or chlorinecontaining etchant gas; (2) the first polycrystalline silicon layer isetched to form the etched first polycrystalline silicon layer within theseasoned plasma reactor chamber; and (3) the seasoning polymer layer iscleaned from the seasoned plasma reactor chamber to provide the cleanedplasma reactor chamber after etching the first polycrystalline siliconlayer to form the etched first polycrystalline silicon layer within theseasoned plasma reactor chamber prior to etching a second substratehaving formed thereover a second polycrystalline silicon layer to forman etched second polycrystalline silicon layer formed over the secondsubstrate within the plasma reactor chamber while employing the plasmaetch method in accord with (1), (2) and (3).
 7. The method of claim 1wherein the substrate is employed within a microelectronic fabricationselected from the group consisting of integrated circuit microelectronicfabrications, ceramic substrate microelectronic fabrications, solar celloptoelectronic microelectronic fabrications, sensor image arrayoptoelectronic microelectronic fabrications and display image arrayoptoelectronic microelectronic fabrications.
 8. The method of claim 1wherein the silicon layer is selected from the group consisting ofmonocrystalline silicon layers, polycrystalline silicon layers andamorphous silicon layers.
 9. The method of claim 1 wherein: uponetching, the silicon layer is masked with a mask layer, and the masklayer is selected from the group consisting of silicon containingdielectric hard mask layers and photoresist mask layers.
 10. The methodof claim 1 wherein the seasoning polymer layer is formed of a materialselected from the group consisting of: silicon and bromine containingseasoning polymer materials; silicon, bromine and oxygen containingseasoning polymer materials; silicon and chlorine containing seasoningpolymer materials; silicon, chlorine and oxygen containing seasoningpolymer materials; silicon, bromine and chlorine containing seasoningpolymer materials; and silicon, bromine, chlorine and oxygen containingseasoning polymer materials.
 11. The method of claim 2 wherein thesubstrate is employed within a microelectronic fabrication selected fromthe group consisting of integrated circuit microelectronic fabrications,ceramic substrate microelectronic fabrications, solar celloptoelectronic microelectronic fabrications, sensor image arrayoptoelectronic microelectronic fabrications and display image arrayoptoelectronic microelectronic fabrications.
 12. The method of claim 2wherein: upon etching, the first monocrystalline silicon layer is maskedwith a mask layer; and the mask layer is selected from the groupconsisting of silicon containing dielectric hard mask layers andphotoresist mask layers.
 13. The method of claim 2 wherein the seasoningpolymer layer is formed of a material selected from the group consistingof: silicon and bromine containing seasoning polymer materials; silicon,bromine and oxygen containing seasoning polymer materials; silicon andchlorine containing seasoning polymer materials; silicon, chlorine andoxygen containing seasoning polymer materials; silicon, bromine andchlorine containing seasoning polymer materials; and silicon, bromine,chlorine and oxygen containing seasoning polymer materials.
 14. Themethod of claim 3 wherein the substrate is employed within amicroelectronic fabrication selected from the group consisting ofintegrated circuit microelectronic fabrications, ceramic substratemicroelectronic fabrications, solar cell optoelectronic microelectronicfabrications, sensor image array optoelectronic microelectronicfabrications and display image array optoelectronic microelectronicfabrications.
 15. The method of claim 3 wherein: upon etching, thepolycrystalline silicon layer is masked with a mask layer; and the masklayer is selected from the group consisting of silicon containingdielectric hard mask layers and photoresist mask layers.
 16. The methodof claim 3 wherein the seasoning polymer layer is formed of a materialselected from the group consisting of: silicon and bromine containingseasoning polymer materials; silicon, bromine and oxygen containingseasoning polymer materials; silicon and chlorine containing seasoningpolymer materials; silicon, chlorine and oxygen containing seasoningpolymer materials; silicon, bromine and chlorine containing seasoningpolymer materials; and silicon, bromine, chlorine and oxygen containingseasoning polymer materials.
 17. The method of claim 1, wherein theseasoned plasma reactor chamber cleaning step, when using an eight inchdiameter substrate, employs: a seasoned plasma reactor chamber pressureof from about 50 to 500 mTorr; a source radio frequency power of fromabout 100 to 200 watts at a source radio frequency of from about 2 to13.56 MHz and a bias power of up to about 500 watts; a seasoned plasmareactor chamber temperature of from about 20 to 200° C.; a nitrogentrifluoride or a sulfur hexafluoride flow rate of from about 10 to 500sccm; a backside cooling gas pressure of from about 1 to 50 torr and aflow rate of from about 2 to 50 sccm; and a magnetic field of up toabout 200 gauss.
 18. The method of claim 2, wherein the seasoned plasmareactor chamber cleaning step, when using an eight inch diametersubstrate, employs: a seasoned plasma reactor chamber pressure of fromabout 50 to 500 mTorr; a source radio frequency power of from about 100to 200 watts at a source radio frequency of from about 2 to 13.56 MHzand a bias power of up to about 500 watts; a seasoned plasma reactorchamber temperature of from about 20 to 200° C.; a nitrogen trifluorideor a sulfur hexafluoride flow rate of from about 10 to 500 sccm; abackside cooling gas pressure of from about 1 to 50 torr and a flow rateof from about 2 to 50 sccm; and a magnetic field of up to about 200gauss.
 19. The method of claim 3, wherein the seasoned plasma reactorchamber cleaning step, when using an eight inch diameter substrate,employs: a seasoned plasma reactor chamber pressure of from about 50 to500 mTorr; a source radio frequency power of from about 100 to 200 wattsat a source radio frequency of from about 2 to 13.56 MHz and a biaspower of up to about 500 watts; a seasoned plasma reactor chambertemperature of from about 20 to 200° C.; a nitrogen trifluoride or asulfur hexafluoride flow rate of from about 10 to 500 sccm; a backsidecooling gas pressure of from about 1 to 50 torr and a flow rate of fromabout 2 to 50 sccm; and a magnetic field of up to about 200 gauss. 20.The method of claim 2, wherein the first polycrystalline silicon layeretch step, when using an eight inch diameter substrate, employs ahydrogen bromide flow rate of from about 10 to 200 sccm.
 21. The methodof claim 3, wherein the first monocrystalline silicon layer etch step,when using an eight inch diameter substrate, employs a hydrogen bromideflow rate of from about 10 to 200 sccm.